In the construction of electronically tuned resonators or oscillators, especially those used in transmitters and the like, and in the front ends of communications receivers a plurality of filters, or resonant circuits, are required to allow the apparatus to operate at any of a variety of channels, or center frequencies. In the prior art a separate filter, or resonant circuit, is provided for each desired center frequency or channel and the entire filter is switched when the apparatus is changed to a different channel. Some attempts have been made at switching a variety of resonant circuits in an oscillator, for example, but this is very difficult to accomplish, especially at higher frequencies. Also, in most instances, the prior art structures require large amounts of power to operate the switching devices and extensive space for the mounting and housing thereof.